Hydrosilylation reaction catalyst

Abstract

A hydrosilylation reaction catalyst prepared from: a prescribed transition metal compound such as iron pivalate, cobalt pivalate, iron acetate, cobalt acetate, or nickel acetate; a ligand comprising t-butylisocyanide or another isocyanide compound; and a borane compound, Grignard reagent, alkoxysilane, or other prescribed promoter makes it possible to promote a hydrosilylation reaction under moderate conditions, and has exceptional handling properties and storage stability.

Description

TECHNICAL FIELD[0001]This invention relates to a hydrosilylation reaction catalyst and more particularly, to a hydrosilylation reaction catalyst formed from a metal compound serving as a catalyst precursor, an isocyanide compound serving as a ligand component, and a promoter.BACKGROUND ART[0002]Hydrosilylation reaction which is addition reaction of a Si—H functional compound to a compound having a carbon-carbon double bond or triple bond is a useful method for the synthesis of organosilicon compounds and an industrially important synthesis reaction.[0003]As the catalyst for hydrosilylation reaction, Pt, Pd and Rh compounds are known. Among others, Pt compounds as typified by Speier's catalyst and Karstedt's catalyst are most commonly used.[0004]While several problems arise with reaction in the presence of Pt compounds as the catalyst, one problem is that upon addition of a Si—H functional compound to terminal olefin, a side reaction due to internal rearrangement of olefin takes plac...

AI Technical Summary

Benefits of technology

[0128]The metal compound from which the hydrosilylation reaction catalyst of the invention is prepared is readily available as a commercial product or by synthesis in a well-known way. The metal compound is quite easy to handle because of no need for storage at low temperature or in an inert gas atmosphere and no need for handling (e.g., metering) in a glove box, and maintains high activity even after long-term exposure to air.

[0129]On the other hand, the isocyanide compound serving as the ligand can also be stored at room temperature, and requires no special equipment upon handling.

[0130]Furthermore, the compound serving as the promoter is readily available as a commercial product or by synthesis in a well-known way.

[0131]Also, since the inventive catalyst does not possess such a ligand as carbonyl group, η4-diene group, η5-cyclopentadienyl group, η6-arene or triene group, it has advantages including shelf stability, ease of handling and high reactivity.

[0132]The catalyst prepared from the metal compound, isocyanide compound and promoter may be used after isolation as a metal complex compound, or it may be prepared in a hydrosilylation reaction system and used therein without isolation.

[0133]If hydrosilylation reaction between a compound containing an aliphatic unsaturated group and a silane or polysiloxane having a Si—H group is carried out in the presence of the catalyst prepared from the metal compound, isocyanide compound and promoter, addition reaction is possible under such conditions as room temperature to 100° C. The catalyst allows the reaction temperature to be lowered or the reaction time to be shortened, as compared with the catalyst prepared without using the promoter. In particular, addition reaction with industrially useful polysiloxanes, trialkoxysilanes and dialkoxysilanes takes place effectively.

Problems solved by technology

While several problems arise with reaction in the presence of Pt compounds as the catalyst, one problem is that upon addition of a Si—H functional compound to terminal olefin, a side reaction due to internal rearrangement of olefin takes place.

Another problem is that the selectivity of α- and β-adducts is low depending on the type of olefin.

The most serious problem is that all the center metals Pt, Pd and Rh are quite expensive noble metal elements.

Although PhSiH3 and Ph2SiH2 add to olefins, more useful trialkylsilanes, alkoxysilanes and siloxanes have poor addition reactivity to olefins.

This method needs some steps until the catalyst is synthesized, including first synthesizing a terpyridine-iron complex as a catalyst precursor and introducing a bistrimethylsilylmethyl group therein at a low temperature, which steps are not easy industrially.

The reaction using the complex, however, suffers from several problems including low reactivity with internal olefin, the use of sodium amalgam consisting of water-sensitive sodium and highly toxic mercury and requiring careful handling for complex synthesis, low stability of the complex compound itself, a need for a special equipment like a glove box for handling, and a need for storage in an inert gas atmosphere such as nitrogen at low temperature.

Non-Patent Documents 9 to 14 report examples of reaction in the presence of cobalt-carbonyl complexes (e.g., Co2(CO)8), but they are unsatisfactory in the product yield and molar ratio of the catalyst per reactant.

Because of low stability, these complex compounds require a special equipment like a glove box for handling and an inert gas atmosphere and a low temperature for storage.

Like the above-cited Non-Patent Documents 6 to 8, there are problems including industrial difficulty of synthesis of a catalyst precursor or synthesis of the complex catalyst from the precursor, low stability of the complex compound itself, and a need for a special equipment for handling.

Likewise, the synthesis is industrially difficult, and the yield of the desired product is less than satisfactory.

For example, a catalyst having a phosphine ligand (Non-Patent Document 18) lacks in selectivity and requires careful handling and storage.

Although this method has the advantage of easy storage and handling of the catalyst, no study is made on reactivity with siloxanes which are more useful from the industrial standpoint.

In addition, rhodium is likewise an expensive noble metal element.

However, reactivity is empirically demonstrated with respect to only platinum, palladium, rhodium and iridium which are expensive metal elements.

Thus the method is not regarded cost effective.

In addition, the metal catalysts coordinated with N-heterocyclic carbene require careful handling because the complex compounds have low storage stability.

These catalysts have inferior reactivity to platinum catalysts and require careful handling because the complex compounds have low storage stability.

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